Well, most of them are just downloading in parallel. There are only a handful of spiders that make a serious attempt at keeping up-to-date on everything, and most of it is governed by the sitemap - Googlebot, Slurp (Yahoo), Bingbot, and any other spider that understands sitemaps should only visit it again if it's been updated in some manner.

That doesn't always happen, but the dumber spiders do get hooked on sessions so they won't necessarily get counted a bajillion times.

Spiders (in the Internet sense) are little programs that search engines use to compile web pages for their search results. As spiders help to steer people towards pages that match what they're looking for, spiders are actually rather beneficial. However, as anything in the public area of Elliquiy can be 'seen' by spiders (and therefore, can be searched for), they are yet another reason to keep private stuff (like contact info) out of the public area.